1. Field of the Invention
The present invention relates to a substrate inspection method, a manufacturing method of a semiconductor device and a substrate inspection apparatus, and is directed to, for example, an inspection of a substrate using a charged particle beam.
2. Related Background Art
Various techniques have been proposed wherein a rectangular electron beam is formed by an electron gun to illuminate a substrate with the electron beam as a primary beam, and a secondary electron, a reflected electron and a back scattering electron which have been generated in accordance with variation in the shape, material and potential of the surface of the substrate are projected as a secondary beam in an expanded form to an electron detection unit by a map/projection optical system, such that an image of the surface of a sample is obtained and thus applied to a defect inspection of a semiconductor pattern (e.g., Japanese Patent Publication Laid-open No. 7-249393 and Japanese Patent Publication Laid-open No. 11-132975).
According to methods disclosed in these patent documents, the secondary beams comprising the secondary electron, the reflected electron and the back scattering electron which have been generated in accordance with the changes in the shape, material and potential of the substrate surface are imaged via the map/projection optical system, and the contrast of a signal of this image allows the sample surface image to be formed. In such an image forming mechanism, the rate of a material of an inspection target to contribute to the contrast (material contrast) of an obtained image is extremely high since efficiency of the secondary beam generation depends on the material of the inspection target. Further, because the secondary beam generated from an edge portion such as minute concave and convex shapes on the substrate surface does not contribute to the imaging, there has been a problem that it is difficult to obtain an image contrast, and that the amount of information is small regarding the concave and convex shapes. Moreover, the track of the generated secondary beam is deflected by an electric field formed immediately on the substrate surface due to, for example, charge-up, and thus the contrast (potential contrast) of the inspection target due to a surface potential is not imaged on the detector, leading to a decreased contrast. There has also been a problem that if, for example, the back scattering electron is used to reduce such influence of an electromagnetic field immediately on the surface, the influence of the electromagnetic field immediately on the surface is indeed reduced, but along with this, inspection sensitivity regarding the electromagnetic field itself on the substrate surface is significantly lowered.